Cg in THAT 1512

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Hey everyone, I'm putting a pre-amp in a project and I was given some THAT 1512 pre-amp chips. It's the first pre-amp I'm building, so I'm still pretty green with this type of stuff, pretty much an electronics noob in general too.

Reading the datasheet, I'm going to build the circuit in Figure 4.

http://www.thatcorp.com/datashts/THAT_1510-1512_Datasheet.pdf

On page 5, it states that Cg must be large enough to at smaller Rg values. My guess is that I'll probably be using <100 ohms at Rg. It recommends 6,800uF, but that doesn't seem right... Seems like that's waaaay too high of a value.

Does anyone have any experience or any advice on how to properly build that circuit?

Thanks!
 
You want the time constant for the RC to be at least a decade lower than the lowest frequency of interest. Let's say the resistor is 100 ohms and you want to go down to 20 Hz. Then a decade below is 2 Hz, so using C = 1/2pifR, we get about 800 uF. If the resistor is smaller, the cap will be proportionately bigger.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.